1. Field of the Invention
The present invention relates to a method of illumination expression of a head up display for a vehicle, and more particularly, to a method of illumination expression of a head up display for a vehicle that illuminates the head up display even when external illumination of the head up display is not input due to an auto light failure.
2. Description of the Prior Art
Generally, a head up display has been used to display various types of information, such as a speed, a location, and a remaining fuel level of an aircraft or a vehicle, on a background of the external environment in the aircraft or other vehicles. A driver may simultaneously view information images, which overlap within the head up display, on a background screen.
Meanwhile, the head up display apparatus applied to the vehicle reflects output images from a reflection mirror and projects the reflected output images to a windshield glass serving as a combinder to help a driver see virtual images outside the windshield glass, thereby providing the driver with driving information. The head up display is embedded in a dash board in front of a driver's seat or is mounted on the dash board.
Since the expressing of the head up display is expressed on a driver's view, the head up display according to the related art sets a predetermined illumination value by recognizing external illuminance with an auto light so as not to hinder the driver's view and performs expression depending on a setting of the head up display.
However, the head up display according to the related art interlocks with an auto light sensor to set an appropriate illumination value associated with the head up display so as to be able to change illumination brightness of the head up display depending on the external illumination, but when the auto light sensor is broken or a signal is not properly transferred due to communication disturbance, the head up display screen sleeps, such that even in the state in which the head up display is not broken, the driver may not normally see the screen, thereby deteriorating marketability.    Patent 1: Korean Patent Laid-Open Publication No. 10-2008-0045849